This invention relates to the field of medical devices and, more particularly, to a continuous ambulatory peritoneal dialysis apparatus (CAPD) wherein a piercing pin or spike of a tube set connected to a container of used dialysis solution is automatically transferred from the clamped port of the container of used solution to the clamped port of a container of fresh dialysis solution with a minimum of spillage of the used dialysis solution in the CAPD apparatus.
One such CAPD apparatus is disclosed in U.S. Pat. No. 4,840,621 which issued Jun. 20, 1989 to the same assignee to whom this application is assigned. To provide an appropriate structural and environmental background for the invention disclosed and claimed herein, the disclosure of said U.S. Pat. No. 4,840,621 is incorporated herein by reference. After a CAPD patient has opened the appropriate clamping devices to permit a used charge of dialysis solution to drain by gravity from his or her peritoneal cavity into an empty container, the port of the used solution container is clamped and mounted in the CAPD apparatus with the spike of the tube set, which is still sealingly mounted in the port of the used solution container, being mounted in a spike holder or cradle of the CAPD apparatus. Upon activation of the motor of the CAPD apparatus, the spike holder and the spike mounted thereon are automatically, by means of a unique transfer mechanism, linearly withdrawn from the clamped port of the used solution container, rotated through 180 degrees, and then linearly moved into seal piercing engagement in a clamped port of a container of fresh dialysis solution.
It is important that the tube set attached to the spike be occluded or otherwise clamped closed as close as possible to the spike prior to the spike being withdrawn from the clamped port of the used solution container to prevent spillage or even flooding of the CAPD apparatus by used solution remaining in the tube set. Although mechanical clamping devices may be provided on the tube set, many patients undergoing continuous ambulatory peritoneal dialysis may be so impaired by failing eyesight, by lessening of their physical strength and dexterity, or by simple forgetfulness that such clamping devices may not be properly activated prior to activation of the CAPD apparatus. It is noted that it may be necessary for a CAPD patient to drain and recharge his or her peritoneal cavity with fresh dialysis solution as often as four times a day so the procedure must be as simple and accident-proof as possible.